JB/T 58651.5-1999

Fastener manufacturers and quality inspection departments use this standard to evaluate the quality grade of machine screw products. The three-level grading system (superior, first-grade, qualified) helps companies control product quality and ensure compliance with national or industry standards. This standard provides a unified quality assessment basis for both suppliers and buyers, contributing to the overall quality improvement of the fastener industry.

紧固件制造企业和质量检验部门使用本标准，对机器螺钉产品进行质量等级评定。通过三级分等（优等品、一等品、合格品），帮助企业控制产品质量水平，确保产品符合国家标准或行业标准。该标准为供需双方提供了统一的质量评价依据，有助于提升紧固件行业的整体质量水平。

This standard specifies the principles and methods for quality grading of machine screw products, adopting a three-level grading system of superior, first-grade, and qualified products. It applies to single-specification product batches accepted according to GB/T 90, covering slotted and cross-recessed screws, special-shaped screws, and captive screws. The standard details sampling items, sampling plans, defect grades, and weighted values, and specifies defect score standards for each grade. Inspection methods include the use of thread gauges, calipers, micrometers, and other tools. This standard provides a unified quality assessment basis for the fastener industry.

本标准规定了机器螺钉类产品质量分等的原则和方法，采用优等品、一等品、合格品三级分等体系。适用于按GB/T 90接收的单一规格产品批，涵盖开槽和十字槽螺钉、异形螺钉及不脱出螺钉。标准详细列出了抽查项目、抽样方案、缺陷等级及加权值，并规定了各等级的缺陷分标准。检验方法包括螺纹量规、卡尺、千分尺等工具的使用。该标准为紧固件行业提供了统一的质量评价依据。